Kiera Jefferson
Plants can be used to reduce noise pollution, a problem that affects millions of people daily and can have adverse health effects. Noise barriers made from trees and other plants can provide respite from unwanted noise by absorbing, deflecting, refracting, or masking sound waves. The physical characteristics of plants, such as their height, branching structure, leaf shape, bark texture, and wood density, play a role in their ability to reduce noise. For example, rough bark and thick, fleshy leaves are particularly effective at absorbing sound due to their dynamic surface area. Additionally, the number of plants, their size, and the surface area of their leaves and overall structure all contribute to their sound-reducing capabilities.
| Characteristics | Values |
|---|---|
| How plants reduce noise | Absorbing, deflecting, refracting, or masking sound waves |
| How much noise can plants reduce? | A 100-foot-wide tree barrier will reduce noise by 5 to 8 decibels (dBA) |
| Best sound barrier plants | Spruce, poplar, and beech |
| How to use plants to reduce noise | Use large planters, place plants near the edges and corners of a space, use screen plants instead of office partitions |
What You'll Learn
Plants absorb, diffract and reflect sound
Plants are a great way to reduce unwanted noise. They are scientifically proven to help absorb, diffract and reflect sound.
Absorption
Plant parts such as stems, leaves, branches, and wood all absorb sound. Rough and thick plant parts like bark and fleshy leaves are particularly effective at sound absorption due to their dynamic surface area. The greater the number of plants, their size, and their surface area, the more sound they will be able to absorb. Plants with more textures in their leaves, branches, vines, and bark will be able to absorb more sound.
Diffraction
At a lower frequency, leaves are able to vibrate, transforming sound waves into other forms of energy and bending the noise into other directions. Because the leaf size is small compared to the noise wavelength, plants are able to reflect the noise towards other surfaces where the sound has reduced. Without plants, the waves would hit rigid walls that do not vibrate, causing the sound to be louder and to echo.
Reflection
Leaves, branches, and trunks all contribute to the reflection of sound waves by creating a physical barrier. Sound waves bounce off surfaces with more density, with harder objects deflecting more sound. Large, rigid tree trunks with dense bark, like oak, are the best sound deflectors. Deflected sound waves can also change direction and interfere with each other, creating a noise-canceling effect.
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Sound wave refraction
When sound waves encounter plants, they can be refracted, or bent, as they pass through or around the plant's structure. This is due to the difference in acoustic properties between the air and the plant material, which can include leaves, branches, stems, and wood. The complex structures of plants, with their varying textures and densities, contribute to the refraction of sound waves.
The degree of refraction depends on the physical characteristics of the plant, such as its height, branching structure, leaf shape and density, bark texture, and wood density. For example, vines on walls or the sides of buildings can effectively refract sound waves, reducing noise levels indoors.
Plants with rough bark and thick, fleshy leaves are particularly effective at refracting sound waves due to their increased surface area and ability to absorb sound energy. Additionally, the ground between trees plays a significant role in sound absorption, as tree roots keep the soil loose, and dead organic matter adds a spongy layer that enhances sound absorption.
The placement of plants also influences their ability to refract sound. For instance, in indoor spaces, placing plants near edges and corners is more effective than placing them in the centre. This is because sound reflects off walls and other hard surfaces, and strategic placement of plants can maximise their sound-refracting capabilities.
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Sound deflection
Plants with rough bark and thick, fleshy leaves are particularly effective at sound deflection due to their dynamic surface area. The greater the number of plants, their size, and their surface area, the better their ability to deflect sound. Vines on walls and the sides of buildings, lawns, ground cover plantings, and green walls are excellent at deflecting sound.
In addition to deflecting sound, plants can also absorb and refract sound waves. The complex structures of tree crowns, for example, can dampen noise pollution, and the You may want to see also Trees and plants can be used to create noise barriers that provide respite from unwanted noise pollution. Strategically placed trees and plants can help reduce noise by absorbing, deflecting, refracting, or masking sound waves. A well-designed 100-foot-wide tree barrier can reduce noise by 5 to 8 decibels (dBA), according to the USDA. Plants reduce noise through sound absorption, deflection, and refraction. Plant parts such as stems, leaves, branches, and wood absorb sound, with rough bark and thick, fleshy leaves being particularly effective due to their dynamic surface area. The number of plants, their size, and the surface area of the leaves and plants themselves all contribute to sound absorption. When sound waves hit a flexible material like plants, the material vibrates, and the waves are transformed into other forms of energy and deflected in other directions. Sound waves can also be refracted when they pass through different mediums. For example, vines on walls and the sides of buildings help refract sound, as do lawns, ground cover plantings, and green walls. How to create a sound barrier with trees and plants The most effective noise barriers have diverse structures that prevent gaps and add varied textures to the environment. In addition to trees, effective sound barriers include shrubs, bushes, vines, and herbaceous plants. The width of the vegetation barrier and its distance from the noise source play a key role in its effectiveness. A buffer planted closer to the noise source will block more noise than one farther away. Broadleaf trees are effective at deflecting sound, but they lose their leaves in winter, resulting in a loss of the sound barrier. Evergreen trees, on the other hand, provide a consistent buffer as they retain their needles or leaves across seasons. They are also fast-growing and can be planted close together, creating a denser barrier. When choosing plants and trees for a sound barrier, select species that will thrive in the local environment and are tolerant of air pollution if placed near roadways. Examples of effective noise-blocking plants include spruce, poplar, beech, arborvitae, privet, holly, and various types of cypress trees. You may want to see also Plants can be used as sound barriers to reduce noise pollution. They absorb, diffract, reflect, and mask sound waves. The effectiveness of plants as sound barriers depends on several factors, including the type of plant, its size, shape, and the physical properties of the room or environment. How Plants Reduce Noise Plant parts such as stems, leaves, branches, and wood all absorb sound. Rough bark and thick, fleshy leaves are particularly good at sound absorption due to their large surface area. The greater the number of plants, their size, and their surface area, the better their ability to absorb sound. Plants with dense foliage that reaches the ground are ideal for sound absorption. Sound waves are reflected off rigid walls, but when they hit a flexible material like plants, the material vibrates and the waves are transformed into other forms of energy and deflected in different directions. This is known as sound deflection. Sound waves can also be refracted by plants. For example, vines on walls or buildings will help refract sound, as will lawns, ground cover, and green walls. Using Plants as Sound Barriers When using plants as sound barriers, it is recommended to use a combination of plant forms, primarily evergreen species with broad leaves and low-growing foliage. Low-growing plants should be placed closest to the source of noise, with taller plants behind them. A third row of plants can provide additional protection and may include flowering or fruiting species. The width of the vegetation barrier and its distance from the source of noise are important factors in its effectiveness. A buffer of plants closer to the noise source will block more noise than one farther away. A mix of plant species and heights can also improve sound deflection. Examples of Sound Barrier Plants Some examples of plants that can be effective sound barriers include: You may want to see also Yes, plants can help reduce noise pollution. They absorb, diffract, reflect, and mask sound waves. Plants reduce noise pollution by absorbing sound waves through their stems, leaves, branches, and wood. Rough bark and thick, fleshy leaves are particularly good at sound absorption due to their large surface area. Some plants that can be used to reduce noise pollution include spruce, poplar, beech, arborvitae, privet, and photinia. When using plants to reduce noise pollution, consider the number of plants, the size of the plants, the surface area of the leaves, and the distance from the source of the noise. A buffer of mixed plant species with varied heights and broadleaf specimens is generally more effective at noise reduction.Trees: Natural Noise Pollution Reducers?
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